Comparative analysis of STR and SNP polymorphism in the populations of sockeye salmon (<Emphasis Type="Italic">Oncorhynchus nerka</Emphasis>) from Eastern and Western Kamchatka

Sockeye salmon samples from five largest lacustrine-riverine systems of Kamchatka Peninsula were tested for polymorphism at six microsatellite (STR) and five single nucleotide polymorphism (SNP) loci. Statistically significant genetic differentiation among local populations from this part of the species range examined was demonstrated. The data presented point to pronounced genetic divergence of the populations from two geographical regions, Eastern and Western Kamchatka. For sockeye salmon, the individual identification test accuracy was higher for microsatellites compared to similar number of SNP markers. Pooling of the STR and SNP allele frequency data sets provided the highest accuracy of the individual fish population assignment.     

Seasonal and interannual variations of sockeye salmon (<Emphasis Type="Italic">Oncorhynchus nerka</Emphasis>) microsatellite DNA in two Kamchatka lake-river systems

Seasonal and interannual variations in the sockeye salmon populations from two lake-river systems of the East and West Kamchatka were studied. Stability of allele and genotypic frequencies of six microsatellite DNA loci in the adjacent generations and spawning populations of the sockeye salmon of the Bol’shaya River was confirmed experimentally. The pairwise intersample differentiation (F _st) of the local sockeye salmon populations from the southwestern Kamchatka coast (Ozernaya and Bol’shaya Rivers) was almost 7 times higher than the corresponding values for the spawning populations of the Bol’shaya River sockeye salmon of the adjacent years; 15 times, for the adjacent Bol’shaya River sockeye salmon generations; and four times, for the seasonal races within the Kamchatka River.     

Genetic diversity of sockeye salmon <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis> Walbaum of Kamchatka and the Commander Islands based on analysis of the variability of microsatellite DNA

The genetic diversity of the resident and migratory forms of sockeye salmon is investigated in 14 populations from various water bodies of Kamchatka and the Commander Islands by ten loci of microsatellite DNA. There are considerable differences in the frequencies of alleles among the populations of kokanee from Lake Kronotskoe, the residual form of sockeye salmon from Lake Kopylie, and other populations analyzed. Clustering of samples corresponds to their geographic position. No differences in the frequencies of alleles of the investigated loci are found between two forms of resident sockeye salmon from Kronotskoe Lake. In the sockeye salmon from the Commander Islands, a relatively low genetic diversity is found, as well as the greatest remoteness from the other Kamchatka group.     

The state of gonads of resident sockeye salmon <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis> from the Tolmachev Reservoir

Morphology of gonads and structure of sex cells in females and males of the resident sockeye salmon Oncorhynchus nerka—kokanee—from Tolmachevskoe Reservoir are investigated. Anomalies in structure of sex cells and structure of oocytes are found. Partial or mass resorpbion of cells in the ovaries of males and testes of males is found, leading to sterility of gonads. The relationship between anomalies found in structure of the sex system of kokanee, changes in biological parameters of fish and the increase of the population abundance is discussed.     

Swimming performance and morphology of juvenile sockeye salmon, <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis>: comparison of inlet and outlet fry populations

We raised two populations of sockeye salmon fry from fertilized eggs in the laboratory and tested the hypothesis that outlet fry populations, fish which must migrate upstream to reach rearing lakes after yolk-sac absorption, have better swimming ability and morphological characteristics conducive to enhanced swimming performance than inlet fry populations, fish which migrate downstream to rearing lakes. Despite being of identical age, fry from the outlet population were larger (approx. 6.7% longer, ~5 mm on average) and more laterally compressed than inlet fry at the time of our initial experiments. Using an open-top box flume, we found that the burst-swimming performance (in cm s⁻¹) of the outlet population was 31% better. We found no differences between populations in prolonged-swimming performance. We were unable to find any direct relationships between measures of swimming performance and size or shape variables, suggesting that the larger, more robust morphology of outlet fry was not responsible for the superior burst ability. Recent biochemical studies indicate outlet fry may be metabolically better provisioned for burst swimming than inlet fry. It is possible that the morphological differences between the populations of fry reflect adaptations needed by adults during their migration and spawning.     

A genetic evaluation of relatedness for broodstock management of captive,endangered Snake River sockeye salmon, <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis>

The use of captive broodstocks is becoming more frequently employed as the number of species facing endangerment or extinction throughout the world increases. Efforts to rebuild the endangered Snake River sockeye salmon, Oncorhynchus nerka, population have been ongoing for over a decade, but the use of microsatellite data to develop inbreeding avoidance matrices is a more recent component to the program. This study used known genealogical relationships among sockeye salmon offspring to test four different pairwise relatedness estimators and a maximum-likelihood (M-L) relatedness estimator. The goal of this study was to develop a breeding strategy with these estimators that would minimize the loss of genetic diversity, minimize inbreeding, and determine how returning anadromous adults are incorporated into the broodstock along with full-term hatchery adults. Results of this study indicated that both the M _xy and R _QG estimators had the lowest Type II error rates and the M-L and R _R estimators had the lowest Type I error rates. An approach that utilizes a combination of estimators may provide the most valuable information for managers. We recommend that the M-L and R _R methods be used to rank the genetic importance of returning adults and the M _xy or R _QG estimators be used to determine which fish to pair for spawning. This approach provides for the best genetic management of this captive, endangered population and should be generally applicable to the genetic management of other endangered stocks with no pedigree.     

Migration patterns and phenotypic diversity of underyearlings of sockeye salmon <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis> in the Ozernaya River basin (Kamchatka)

Migratory behavior, size composition, and feeding patterns of the underyearlings of sockeye salmon Oncorhynchus nerka from different intraspecific phenotypic groups in the Ozernaya River basin are studied. Complex organization of main phenotypic groups is demonstrated: several labile spatial-temporal groups are defined within them. The discovered phenotypic polymorphism is temporal and manifested by the sockeye salmon underyearlings only during the period in which they reach the main rearing grounds.     

Structure of the school of sock-eyed salmon <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis> from the Apuka River (the Northeastern Kamchatka)

Results of study of sock-eyed salmon Oncorhynchus nerka from the Apuka River—the largest river of the northeast of Kamchatka—inflowing Olyutorskii Bay of the Bering Sea are presented. It is established that the school of the Apuka River is represented by the early-run sock-eyed salmon that spawns in Lake Vatyg-Gytkhyn located in the lower part of the basin and by individuals of the later run that spawn in the upper reaches of the river. Early-run sock-eyed salmon appears in the river with signs of spawning changes and a high value of gonadosomatic index (GSI). Late-run sock-eyed salmon migrates to the river without signs of spawning changes and with a relatively low GSI. The age composition of spawners of the early- and late-run sock-eyed salmon is different.     

Age structure and growth of resident kokanee <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis> of natural and introduced populations in lakes of Kamchatka

The analysis of growth of kokanee Oncorhynchus nerka demonstrated that there are differences in several indices between the natural population of Kronotskoe Lake and artificial populations of Tolmachevskoe and Klyuchevoe lakes. The highest specific rate of growth was recorded for individuals in Kronotskoe Lake; the lowest, in Tolmachevskoe and Klyuchevoe lakes (in 2006). For the Tolmachev kokanee, a multiyear tendency for a decrease in the gain of scales in generations was found, which is determined by the persisting formation of the population and the depletion of food resources. A considerable effect on the process of formation of the Tolmachev population of kokanee is made by commercial activity and the related transformation of the lake into a reservoir.     

Physiological and molecular endocrine changes in maturing wild sockeye salmon, <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis>, during ocean and river migration

Maturing adult sockeye salmon Oncorhynchus nerka were intercepted while migrating in the ocean and upstream in freshwater over a combined distance of more than 1,300 km to determine physiological and endocrine changes associated with ionoregulation. Sockeye migrating through seawater and freshwater showed consistent declines in gill Na⁺/K⁺-ATPase (NKA) activity, plasma osmolality and plasma chloride concentration. In contrast, plasma sodium concentration became elevated in seawater as fish approached the river mouth and was then restored after sockeye entered the river. Accompanying the movement from seawater to freshwater was a significant increase in mRNA for the NKA α1a subunit in the gill, with little change in the α1b subunit. Potential endocrine signals stimulating the physiological changes during migration were assessed by measuring plasma cortisol and prolactin (Prl) concentrations and quantifying mRNA extracted from the gill for glucocorticoid receptors 1 and 2 (GR1 and GR2), mineralocorticoid receptor (MR), growth hormone 1 receptor (GH1R), and prolactin receptor (PrlR). Plasma cortisol and prolactin concentrations were high in seawater suggesting a preparatory endocrine signal before freshwater entry. Generally, the mRNA expression for GR1, GR2 and MR declined during migration, most notably after fish entered freshwater. In contrast, PrlR mRNA increased throughout migration, particularly as sockeye approached the spawning grounds. A highly significant association existed between gill PrlR mRNA and gill NKA α1a mRNA. GH1R mRNA also increased significantly, but only after sockeye had migrated beyond tidal influence in the river and then again just before the fish reached the spawning grounds. These findings suggest that cortisol and prolactin stimulate ionoregulation in the gill as sockeye salmon adapt to freshwater.     

Reproduction ecology of masu salmon <Emphasis Type="Italic">Oncorhynchus masou</Emphasis> in the Kol basin (Western Kamchatka)

In the Kol basin, one of the typical salmon rivers of Western Kamchatka, special traits of reproduction ecology of masu salmon Oncorhynchus masou are studied (characteristics and behavior of spawners during spawning, localization of spawning grounds, topography and hydrology of redds, and interaction with other species of salmonids). The masu salmon spawns in the Kol basin in tributaries of the upper reaches of the river and only in downwelling. Spawning grounds of masu samlmon are confined to stretches with overhanging banks, log jams creating shelters for spawners and favorable hydrological conditions for spawning and egg development. All over its range, masu salmon requires similar conditions for reproduction. In the north of its range, in Kamchatka, masu salmon retains the properties of the most warm-water species in the genus Oncorhynchus and selects for spawning the grounds characterized by the highest temperature in the period of spawning and development.     

Morphological diversity of sockeye salmon (<Emphasis Type="Italic">Oncorhynchus nerka</Emphasis> (Walbaum)) of the Kamchatka River

A method based on morphological characters is proposed to evaluate biological diversity of a sockeye salmon population. In all samples, morphological diversity of males is greater than that of females. In addition, the inter-annual dynamics determined on the basis of separate morphological characters differs in individuals of different sex. The necessity of studying biological diversity for preserving population homeostasis is also considered.     

Formation of scale structure in lacustrine sock-eyed salmon <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis> from water bodies of Kamchatka and determination of its age

The formation of the first annual zone in three populations of resident sock-eyed salmon—kokanee Oncorhynchus nerka of Kamchatka—has been studied. The length of fingerlings in mid-August did not reach 30 mm; in most analyzed juveniles, the remains of the yolk sac were present. In early September in lakes Tolmachevskoe and Kronotskoe, the length of the fingerlings was about 40 mm. The scales in fish from different populations begin to form in early September. Towards November, no more than nine sclerites are formed; a similar amount has been recorded at the beginning of summer also in fingerlings. When scales of adult fish are studied, there are 4 to 19 sclerites in the first annual zone. Apparently, the first annual ring does not form in a considerable portion of fingerlings.     

Variation of mitochondrial DNA in chinook salmon <Emphasis Type="Italic">Oncorhynchus tschawytscha</Emphasis> Walbaum populations from Kamchatka

The variation in mitochondrial DNA (mtDNA) structure among chinook salmon Oncorhynchus tschawytscha Walbaum populations from Kamchatka was inferred from restriction length polymorphism analysis using eight restriction endonucleases. The nucleotide sequence variation in three amplified mtDNA regions was examined at seven polymorphic restriction sites in 579 fish from 13 localities. Based on the frequencies of 11 combined haplotypes and the number of nucleotide substitutions, the among-and within-population variation was estimated. The heterogeneity test showed highly significant differences among all the populations. The estimated maximum time of independent divergence of the asian chinook salmon populations, whose differences was about 0.02% nucleotide substitutions, did not exceed 10 000–20 000 years. Apparently, the retreat of the late Pleistocene glacier triggered spreading, recolonization, and formation of the present-day pattern of the species subdivision into structural components.     

Seasonal races of chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> and their interrelations in Kamchatka Rivers

Dates of migration and spawning, size-age structure, and fecundity of seasonal races of chum salmon Oncorhynchus keta from the Kol River are reviewed, those of early summer, late summer, and autumn races, as well as localization and structure of their spawning grounds, bed-sediment particle size in the redds, hydrological and thermal conditions on spawning grounds, and meristic characters of races. Special traits of reproduction of seasonal races within the species range and in Kamchatka in particular are discussed. The number of seasonal races in rivers depends on the presence of various habitats suitable for spawning. In rivers with complicated hydrogeomorphological structure, the number of seasonal races increases. Variations of types of seasonal races in a particular river and in the whole species area are epigenetic, i.e., they depend on the hereditary genetic program and presence of conditions providing its realization via various channels.     

Seasonal dynamics of degree of pronunciation of smoltification changes and its dependence on body size in hatchery reared juvenile sockeye salmon <Emphasis Type="Italic">Oncorhynchus nerka</Emphasis> from the Bolshaya river basin (Western Kamchatka)

According to the aggregate of the characteristics (survival in 40‰ sea water for 24 hours, loss of body weight at the expense of dehydratation in 30‰ sea water for 24 hours, dynamics of blood osmolarity and hematological characteristics in three-day 30‰ tests, activity of gill Na⁺,K⁺-ATPase in the fresh water), hatchery reared juveniles of rheophilic sockeye salmon (Western Kamchatka, fish hatcheries Malkinskii and Ozerki) are divided into three groups, i.e., parrs, presmolts, and smolts, whose relation naturally changes with the growth of body weight during the spring-summer period of growth. It is established that the parrs conform to a body weight less than 1.25 g, presmolts conform to that from 2 to 4 g, and smolts conform to that more than 4 g. The first smolts under the fish hatchery conditions appear in the second ten-day period of April, in mass they appear in the end of April, and decreasing portion of the smolts in the juveniles with the weight of 2–4 g begins in early May. The quantitative criteria for division of juveniles according to the degree of their readiness to dwelling in the sea and recommendations for optimal terms of release with due account of the season and body size are worked out.     

The effects of experimental energy depletion on the physiological condition and survival of adult sockeye salmon (<Emphasis Type="Italic">Oncorhynchus nerka</Emphasis>) during spawning migration

In 2005 and 2006, adult sockeye salmon (Oncorhynchus nerka) were captured en route to spawning grounds and placed in either a slow (∼ 0.1 m·s⁻¹) or fast (∼0.4 m·s⁻¹) water velocity treatment for 18 days in order to assess how migrational energy depletion during the final stages of maturation affected physiological condition and survival. Fish in the fast treatment utilized more energy than the slow treatment in 2005 (0.91 MJ kg⁻¹ vs. 0.43 MJ kg⁻¹; P = 0.010), and 2006 (0.72 MJ kg⁻¹ vs. 0.37 MJ kg⁻¹; P = 0.021). Non-treatment fish captured upon arrival at spawning grounds showed energy levels intermediate to the two treatments in 2005 and lower than both in 2006, suggesting that energy use during the treatments were within levels normally experienced by this population. No differences in survival were found between treatments (P > 0.05), although females had lower survival than males in both years (both P < 0.01). After 18 days, surviving fish from the fast treatment showed signs of elevated physiological stress relative to fish from the slow treatment. Specifically, plasma osmolality was lower in fast fish in 2005 (P < 0.001), as was plasma chloride in both years (both P < 0.02). In 2006, plasma lactate was higher (P = 0.014) in fast fish. Within the ranges of energetic depletion that were examined here, a more energy-intensive migration can have a substantial influence on the physiological condition and stress of adult sockeye salmon, but not on survival.     

Genetic population structure of central Oregon Coast coho salmon (<Emphasis Type="Italic">Oncorhynchus kisutch</Emphasis>)

We surveyed microsatellite variation from 22 spawning populations of coho salmon (Oncorhynchus kisutch) from the Oregon Coast to help identify populations for conservation planning. All of our samples were temporally replicated, with most samples obtained in 2000 and 2001. We had three goals: (1) to confirm the status of populations identified on the basis of spawning location and life history; (2) to estimate effective population sizes and migration rates in order to determine demographic independence at different spatial scales; and (3) to determine if releases of Washington hatchery coho salmon in the 1980's into Oregon Coast streams resulted in measurable introgression into nearby wild Oregon Coast coho populations. For the last question, our study included a hatchery broodstock sample from 1985, after the Puget Sound introduction, and a 1975 sample taken from the same area prior to the introduction. Our results generally supported previously hypothesized population structure. Most importantly, we found unique lake-rearing groups identified on the basis of a common life-history type were genetically related. Estimates of immigrant fraction using several different methods also generally supported previously identified populations. Estimates of effective population size were highly correlated with estimates of spawning abundance. The 1985 hatchery sample was genetically similar to contemporary Washington samples, and the contemporary Oregon Coast samples were similar to the 1975 Oregon Coast sample, suggesting that introductions of Washington coho salmon did not result in large scale introgression into Oregon populations.     

First report of <Emphasis Type="Italic">Ichthyophonus hoferi</Emphasis> infection in young coho salmon <Emphasis Type="Italic">Oncorhynchus kisutch</Emphasis> (Walbaum) at a fish hatchery in Kamchatka

Resting spores of Ichthyophonus hoferi (50–230 μm in diameter) were found in the kidney, heart, liver, skeletalal muscles, exocrine pancreas, and connective and fatty tissues of young coho salmon Oncorhynchus kisutch from the Vilyuisky fish hatchery. In 10% of the fish, there were granulomas and giant cells in these organs. This is the first report of Ichthyophonus infection in Kamchatka.